What are antioxidants?
The components that act as antioxidants protect the body's cells against damage caused by oxidation by providing electrons to free radicals. Free radicals are substances naturally generated by the body during the conversion of food into energy, but also after physical activity or exposure to cigarette smoke, pollution, and the sun. Oxidative stress, caused by a chronic excessive amount of free radicals in the body, can damage cells and lead to chronic diseases such as cancer, heart disease, cognitive decline, etc.
Antioxidants and Health
Antioxidants are substances naturally present in certain foods, but they are also found in the form of supplements. To date, studies do not support the claim that antioxidant supplementation provides substantial protection against chronic diseases (e.g., heart disease, cancer, etc.). Indeed, many studies on antioxidant supplements show no health benefits, and high doses of antioxidant supplements may even be harmful in some cases.
On the other hand, several pieces of evidence suggest that the consumption of fruits, vegetables, and whole grains, all rich in natural antioxidants, offers protection against several aging-related diseases. For example, prospective epidemiological studies show that higher consumption of fruits, vegetables, and legumes is associated with a lower risk of chronic diseases related to oxidative stress, such as cardiovascular diseases and cancer.
This difference between antioxidant supplements and natural antioxidants could be due to the fact that antioxidants tend to be more effective when combined with other components present in foods. However, it is not exactly known whether this protective effect is due to the antioxidants themselves, other substances present in foods, or a combination of several factors.
What are the best dietary sources of antioxidants?
The most common antioxidant components include vitamins C and E, carotenoid pigments (e.g., beta-carotene, lycopene), as well as the mineral selenium. Added to this list are other related carotenoids, as well as manganese, glutathione, coenzyme Q10, lipoic acid, flavonoids, phenols, polyphenols, phytoestrogens, and many others. They are mainly found in plant-based foods, especially in fruits and vegetables, but also in whole grains, nuts, seeds, and legumes.
Here is a list of some of the best food sources of antioxidants:
Vitamin C: Broccoli, spinach, Brussels sprouts, cantaloupe, cauliflower, collard greens, lemon, kiwi, strawberry, raspberry, mango, blueberry, papaya, guava, grapefruit, sweet potato, tomato, and red bell pepper.
Vitamin E: Almond, avocado, Swiss chard, peanut, fish (e.g., mackerel, salmon, tuna), wheat germ, spinach, and sunflower seed.
Phenolic compounds:
- Quercetin (e.g.: apples, red wine, onions)
- Catechins or flavonoids (e.g.: tea, cocoa, berries, such as blueberries, strawberries, raspberries, cranberries, etc.)
- Resveratrol (ex.: red and white wine, grapes, berries, peanuts)
- Coumaric acid (ex.: spices, berries)
- Anthocyanins (ex.: blueberries, strawberries)
Carotenoids (e.g., beta-carotene, lycopene): Broccoli, carrot, tomato, tangerine, papaya, sweet potato, abricot, asparagus, beetroot, curly green cabbage (kale), mango, orange, pêche, pumpkin, spinach, cantaloupe, and melon d’water.
Curcuminoids: turmeric
Selenium: Brazil nuts, fish, seafood, poultry, eggs, beef, and legumes.
References
- https://www.hsph.harvard.edu/nutritionsource/antioxidants/
- https://www.nccih.nih.gov/health/antioxidants-in-depth
- https://www.unlockfood.ca/en/Articles/Vitamins-and-Minerals/What-you-need-to-know-about-antioxidants.aspx
- https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/multimedia/antioxidants/sls-20076428
- Whitney, Eleanor N., et al. “The Antioxidant Nutrients. Understanding Nutrition, Nelson Education, Toronto, 2013, pp. 380–406.
Article written by:
Marie-Noël Marsan, Nutritionist